Vitis AI Examples - 1.4 English

Vitis AI User Guide (UG1414)
Document ID
UG1414
Release Date
2021-07-22
Version
1.4 English
Vitis AI provides several C++ and Python examples to demonstrate the use of the unified cloud-edge runtime programming APIs.
Note: The sample code helps you get started with the new runtime (VART). They are not meant for performance benchmarking.
To familiarize yourself with the unified APIs, use the VART examples. These examples are only to understand the APIs and do not provide high performance. These APIs are compatible between the edge and cloud, though cloud boards may have different software optimizations such as batching and on the edge would require multi-threading to achieve higher performance. If you desire higher performance, see the Vitis AI Library samples and demo software.

If you want to do optimizations to achieve high performance, here are some suggestions:

  1. Rearrange the thread pipeline structure so that every DPU thread has its own "DPU" runner object.
  2. Optimize display thread so that when DPU FPS is higher than display rate, skipping some frames. 200FPS is too high for video display.
  3. Pre-decoding. The video file might be H.264 encoded. The decoder is slower than the DPU and consumes a lot of CPU resources. The video file has to be first decoded and transformed into raw format.
  4. Batch mode on Alveo boards need special consideration as it may cause video frame jittering. ZCU102 has no batch mode support.
  5. OpenCV cv::imshow is slow, so you need to use libdrm.so. This is only for local display, not through X server.

The following table below describes these Vitis AI examples.

Table 1. Vitis AI Examples
ID Example Name Models Framework Notes
1 resnet50 ResNet50 Caffe Image classification with Vitis AI unified C++ APIs.
2 resnet50_mt_py ResNet50 TensorFlow Multi-threading image classification with Vitis AI unified Python APIs.
3 inception_v1_mt_py Inception-v1 TensorFlow Multi-threading image classification with Vitis AI unified Python APIs.
4 pose_detection SSD, Pose detection Caffe Pose detection with Vitis AI unified C++ APIs.
5 video_analysis SSD Caffe Traffic detection with Vitis AI unified C++ APIs.
6 adas_detection YOLO-v3 Caffe ADAS detection with Vitis AI unified C++ APIs.
7 segmentation FPN Caffe Semantic segmentation with Vitis AI unified C++ APIs.

The typical code snippet to deploy models with Vitis AI unified C++ high-level APIs is as follows:

// get dpu subgraph by parsing model file
auto runner = vart::Runner::create_runner(subgraph, "run");
//populate input/output tensors
auto job_id = runner->execute_async(inputsPtr, outputsPtr);
runner->wait(job_id.first, -1);
//process outputs

The typical code snippet to deploy models with Vitis AI unified Python high-level APIs is shown below:

dpu_runner = runner.Runner(subgraph，"run")
# populate input/output tensors
jid = dpu_runner.execute_async(fpgaInput, fpgaOutput)
dpu_runner.wait(jid)
# process fpgaOutput